Goal:
  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  x : A
  xs : list A
  h : ∀ y : C, Q y → ∥ All (P y) (x :: xs) ∥
  H : (λ (l : list A) (Hl : ∀ y : C, Q y → ∥ All (P y) l ∥) (x : list B),
         ∀ (H := CoreTactics.block) (l0 : list A) 
           (Hl0 : ∀ y : C, Q y → ∥ All (P y) l0 ∥),
           {| pr1 := l; pr2 := Hl |} = {| pr1 := l0; pr2 := Hl0 |}
           → x = map_All fn l0 Hl0
             → let H0 := CoreTactics.block in #|map_All fn l0 Hl0| = #|l0|)
        xs (map_All_obligation_2 x xs h)
        (map_All fn xs (map_All_obligation_2 x xs h))
  ============================
   (let H := CoreTactics.block in #|map_All fn (x :: xs) h| = #|x :: xs|)


DEBUG:Going to execute:
fail 1

Goals:
  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  Hl : ∀ y : C, Q y → ∥ All (P y) [] ∥
  ============================
   (let H := CoreTactics.block in #|map_All fn [] Hl| = #|[]|)

  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  x : A
  xs : list A
  h : ∀ y : C, Q y → ∥ All (P y) (x :: xs) ∥
  H : (λ (l : list A) (Hl : ∀ y : C, Q y → ∥ All (P y) l ∥) (x : list B),
         ∀ (H := CoreTactics.block) (l0 : list A) 
           (Hl0 : ∀ y : C, Q y → ∥ All (P y) l0 ∥),
           {| pr1 := l; pr2 := Hl |} = {| pr1 := l0; pr2 := Hl0 |}
           → x = map_All fn l0 Hl0
             → let H0 := CoreTactics.block in #|map_All fn l0 Hl0| = #|l0|)
        xs (map_All_obligation_2 x xs h)
        (map_All fn xs (map_All_obligation_2 x xs h))
  ============================
   (let H := CoreTactics.block in #|map_All fn (x :: xs) h| = #|x :: xs|)


DEBUG:Going to execute:
cbn beta iota
            delta [Prop.Logic.transport Logic.eq_elim Logic.eq_elim_r eq_rect
                  DepElim.pack_sigma_eq DepElim.pack_sigma_eq_nondep] 
            in *
Level 3: Backtrace:

Tactic failure (level 1).
Level 2: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.

Goals:
  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  Hl : ∀ y : C, Q y → ∥ All (P y) [] ∥
  ============================
   (let H := CoreTactics.block in #|map_All fn [] Hl| = #|[]|)

  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  x : A
  xs : list A
  h : ∀ y : C, Q y → ∥ All (P y) (x :: xs) ∥
  H : ∀ (H := CoreTactics.block) (l : list A) (Hl : 
                                               ∀ y : C, 
                                                 Q y → ∥ All (P y) l ∥),
        {| pr1 := xs; pr2 := map_All_obligation_2 x xs h |} =
        {| pr1 := l; pr2 := Hl |}
        → map_All fn xs (map_All_obligation_2 x xs h) = map_All fn l Hl
          → let H0 := CoreTactics.block in #|map_All fn l Hl| = #|l|
  ============================
   (let H := CoreTactics.block in #|map_All fn (x :: xs) h| = #|x :: xs|)


DEBUG:Going to execute:
DepElim.simplify_IH_hyps

Goals:
  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  Hl : ∀ y : C, Q y → ∥ All (P y) [] ∥
  ============================
   (let H := CoreTactics.block in #|map_All fn [] Hl| = #|[]|)

  
  A : Type
  B : Type
  C : Type
  Q : C → Type
  P : C → A → Prop
  fn : ∀ x : A, (∀ y : C, Q y → P y x) → B
  x : A
  xs : list A
  h : ∀ y : C, Q y → ∥ All (P y) (x :: xs) ∥
  H : ∀ (H := CoreTactics.block) (l : list A) (Hl : 
                                               ∀ y : C, 
                                                 Q y → ∥ All (P y) l ∥),
        {| pr1 := xs; pr2 := map_All_obligation_2 x xs h |} =
        {| pr1 := l; pr2 := Hl |}
        → map_All fn xs (map_All_obligation_2 x xs h) = map_All fn l Hl
          → let H0 := CoreTactics.block in #|map_All fn l Hl| = #|l|
  ============================
   (let H := CoreTactics.block in #|map_All fn (x :: xs) h| = #|x :: xs|)


DEBUG:Going to execute:
repeat
            match goal with
            | hyp:context [ CoreTactics.block ]
              |- _ =>
                  cbn beta in hyp; eqns_specialize_eqs_block hyp;
                   cbn[eq_rect_r eq_rect] in hyp
            end